PLATTSBURGH — Mountain Lake PBS is working on putting up a temporary tower to replace the 400-foot broadcast tower that fell down earlier this week.The Plattsburgh-based station still doesn't know what caused the tower, located on Lyon Mountain in the Town of Saranac, to collapse, but it was insured, Mountain Lake Director of Communications Rhonda Santos said Friday."We plan to rebuild. We are working on a temporary solution to return to broadcasting as soon as possible. Long-term, the replacement of the tower is expected to take place this summer."Mountain Lake, which operates WCFE-TV on analog channel 57 and digital channel 38, is still feeding its signal directly to Charter Cable in the Plattsburgh area but is off the air in the rest of the region.Mountain Lake was broadcasting its public-television program schedule 24 hours a day, seven days a week.Santos said no other towers are near the WCFE tower, but the transmitter building at the base of the tower was damaged when the tower fell over. Mountain Lake Director of Engineering Charlie Zarbo said the tower was so damaged it can't be salvaged.Replacement costs are expected to exceed $1 million, Santos said.It will cost "over $1 million to build. However, because our tower site on Lyon Mountain is so remote, this will mean additional costs."The tower was believed to be in good shape, Santos said."We recently spent $1.5 million to upgrade to digital and reinforce the tower. Our tower received two certifying reviews in the last year."